Merge commit '6e92d2345e8231a44556ce7d416451f5f3e6c398' as 'engine262'

engine262/src/runtime-semantics/OptionalExpression.mts

@@ -0,0 +1,128 @@
+import { ReferenceRecord, Value } from '../value.mts';
+import { Evaluate, type ExpressionEvaluator } from '../evaluator.mts';
+import { Q, X } from '../completion.mts';
+import { IsInTailPosition, StringValue } from '../static-semantics/all.mts';
+import { OutOfRange } from '../helpers.mts';
+import type { ParseNode } from '../parser/ParseNode.mts';
+import {
+  EvaluateCall,
+  EvaluatePropertyAccessWithExpressionKey,
+  EvaluatePropertyAccessWithIdentifierKey,
+} from './all.mts';
+import { GetValue, MakePrivateReference } from '#self';
+
+/** https://tc39.es/ecma262/#sec-optional-chaining-evaluation */
+//   OptionalExpression :
+//     MemberExpression OptionalChain
+//     CallExpression OptionalChain
+//     OptionalExpression OptionalChain
+export function* Evaluate_OptionalExpression({ MemberExpression, OptionalChain }: ParseNode.OptionalExpression) {
+  // 1. Let baseReference be the result of evaluating MemberExpression.
+  const baseReference = Q(yield* Evaluate(MemberExpression));
+  // 2. Let baseValue be ? GetValue(baseReference).
+  const baseValue = Q(yield* GetValue(baseReference));
+  // 3. If baseValue is undefined or null, then
+  if (baseValue === Value.undefined || baseValue === Value.null) {
+    // a. Return undefined.
+    return Value.undefined;
+  }
+  // 4. Return the result of performing ChainEvaluation of OptionalChain with arguments baseValue and baseReference.
+  return yield* ChainEvaluation(OptionalChain, baseValue, X(baseReference));
+}
+
+/** https://tc39.es/ecma262/#sec-optional-chaining-chain-evaluation */
+//   OptionalChain :
+//     `?.` Arguments
+//     `?.` `[` Expression `]`
+//     `?.` IdentifierName
+//     `?.` PrivateIdentifier
+//     OptionalChain Arguments
+//     OptionalChain `[` Expression `]`
+//     OptionalChain `.` IdentifierName
+//     OptionalChain `.` PrivateIdentifier
+function* ChainEvaluation(node: ParseNode.OptionalChain, baseValue: Value, baseReference: Value | ReferenceRecord): ExpressionEvaluator {
+  const {
+    OptionalChain,
+    Arguments,
+    Expression,
+    IdentifierName,
+    PrivateIdentifier,
+  } = node;
+  if (Arguments) {
+    if (OptionalChain) {
+      // 1. Let optionalChain be OptionalChain.
+      const optionalChain = OptionalChain;
+      // 2. Let newReference be ? ChainEvaluation of optionalChain with arguments baseValue and baseReference.
+      const newReference = Q(yield* ChainEvaluation(optionalChain, baseValue, baseReference));
+      // 3. Let newValue be ? GetValue(newReference).
+      const newValue = Q(yield* GetValue(newReference));
+      // 4. Let thisChain be this OptionalChain.
+      const thisChain = node;
+      // 5. Let tailCall be IsInTailPosition(thisChain).
+      const tailCall = IsInTailPosition(thisChain);
+      // 6. Return ? EvaluateCall(newValue, newReference, Arguments, tailCall).
+      return Q(yield* EvaluateCall(newValue, newReference, Arguments, tailCall));
+    }
+    // 1. Let thisChain be this OptionalChain.
+    const thisChain = node;
+    // 2. Let tailCall be IsInTailPosition(thisChain).
+    const tailCall = IsInTailPosition(thisChain);
+    // 3. Return ? EvaluateCall(baseValue, baseReference, Arguments, tailCall).
+    return Q(yield* EvaluateCall(baseValue, baseReference, Arguments, tailCall));
+  }
+  if (Expression) {
+    if (OptionalChain) {
+      // 1. Let optionalChain be OptionalChain.
+      const optionalChain = OptionalChain;
+      // 2. Let newReference be ? ChainEvaluation of optionalChain with arguments baseValue and baseReference.
+      const newReference = Q(yield* ChainEvaluation(optionalChain, baseValue, baseReference));
+      // 3. Let newValue be ? GetValue(newReference).
+      const newValue = Q(yield* GetValue(newReference));
+      // 4. If the code matched by this OptionalChain is strict mode code, let strict be true; else let strict be false.
+      const strict = node.strict;
+      // 5. Return ? EvaluatePropertyAccessWithExpressionKey(newValue, Expression, strict).
+      return Q(yield* EvaluatePropertyAccessWithExpressionKey(newValue, Expression, strict));
+    }
+    // 1. If the code matched by this OptionalChain is strict mode code, let strict be true; else let strict be false.
+    const strict = node.strict;
+    // 2. Return ? EvaluatePropertyAccessWithExpressionKey(baseValue, Expression, strict).
+    return Q(yield* EvaluatePropertyAccessWithExpressionKey(baseValue, Expression, strict));
+  }
+  if (IdentifierName) {
+    if (OptionalChain) {
+      // 1. Let optionalChain be OptionalChain.
+      const optionalChain = OptionalChain;
+      // 2. Let newReference be ? ChainEvaluation of optionalChain with arguments baseValue and baseReference.
+      const newReference = Q(yield* ChainEvaluation(optionalChain, baseValue, baseReference));
+      // 3. Let newValue be ? GetValue(newReference).
+      const newValue = Q(yield* GetValue(newReference));
+      // 4. If the code matched by this OptionalChain is strict mode code, let strict be true; else let strict be false.
+      const strict = node.strict;
+      // 5. Return ! EvaluatePropertyAccessWithIdentifierKey(newValue, IdentifierName, strict).
+      return X(EvaluatePropertyAccessWithIdentifierKey(newValue, IdentifierName, strict));
+    }
+    // 1. If the code matched by this OptionalChain is strict mode code, let strict be true; else let strict be false.
+    const strict = node.strict;
+    // 2. Return ! EvaluatePropertyAccessWithIdentifierKey(baseValue, IdentifierName, strict).
+    return X(EvaluatePropertyAccessWithIdentifierKey(baseValue, IdentifierName, strict));
+  }
+  if (PrivateIdentifier) {
+    if (OptionalChain) {
+      // 1. Let optionalChain be OptionalChain.
+      const optionalChain = OptionalChain;
+      // 2. Let newReference be ? ChainEvaluation of optionalChain with arguments baseValue and baseReference.
+      const newReference = Q(yield* ChainEvaluation(optionalChain, baseValue, baseReference));
+      // 3. Let newValue be ? GetValue(newReference).
+      const newValue = Q(yield* GetValue(newReference));
+      // 4. Let fieldNameString be the StringValue of PrivateIdentifier.
+      const fieldNameString = StringValue(PrivateIdentifier);
+      // 5. Return ! MakePrivateReference(nv, fieldNameString).
+      return X(MakePrivateReference(newValue, fieldNameString));
+    }
+    // 1. Let fieldNameString be the StringValue of PrivateIdentifier.
+    const fieldNameString = StringValue(PrivateIdentifier);
+    // 2. Return ! MakePrivateReference(bv, fieldNameString).
+    return X(MakePrivateReference(baseValue, fieldNameString));
+  }
+  throw new OutOfRange('ChainEvaluation', node);
+}